Multiplex telephony.



Ho. $55.65!. Patented Aug. 7, I900.

E. A. FALLER. MULTIPLE X TELEPHONY.

(Application filed Apr. 27, 1900.] (No Model.) 2 Shaft-Shee l.

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. No. 655,65l. Patented Aug. 7, I900. E. A. FALLER. MULTIPLEX TELEPHONY.

(Applicatiox; filed Apr. 27, 1900.) (No Model.) 2 Sheefs-Sh88t 2.

Inventor [R /EST A. Hume THE NORRIS Pirsns co.. worou'mouwnsnmnmu, a. c.

rrnn STATES PATENT Orrion.

ERNEST A. FALLER, OF SAN FRANCISCO, CALIFORNIA, ASSIGNOR OF ONE- I'IALF TO JAMES W. Cl-IISIIOLM, OF SAME PLACE.

MULTIPLEX TELEPHONY.

SPECIFICATION forming part of Letters Patent No. 655,651, dated August '7, 1900. Application filed April 2'7, 1900 Serial No. 14,605. (No model.)

T at whom it may concern:

Be it known thatI, ERNEST A. FALLER, a citizen of the German Empire, residing at San Francisco, California, have invented cer- 5 tain new and useful Improvements in Multiplex Telephony,of which the following is a specification.

In present telephone practice an independent metallic circuit or grounded line is re- IO quired for each pair of subscribers wishing to enter into telephonic communication.

The object of my invention is to provide means whereby communication may be established and a plurality of conversations may be carried on over one metallic circuitor grounded line and means to make such individual conversations non-interfering. I hereby effect not only a great saving of lines or conductors, but also secure absolute sezo crecy of communication between two stations, making it impossible for outside parties to listen to the conversation thus carried on. In my system I' provide instruments in the various stations adjustable asto their ability 2 5 to send and select voice-currents, and the adjustment of these instruments is automatically effected through the manipulations necessary to establish communication.

My invention consists, essentially, in causing the instruments which are to be used in transmitting the conversation to sympathize or agree as to their electrical conditions when the same are brought from their condition of rest or inactivity into use and at the same 3 5 time causing certain adjustments to take place in all the instruments which are not Wanted, so that upon the next pair of instruments being brought into use their electrical conditions, while mutually harmonizing, will 40 differ from those of the pair already in use, and this same action takes place in respect to the idle instruments whenever another new pair of instruments is brought into use. It will be seen that any idle instrument at one end of the line can establish communication with any idle instrument at the other end of the line while a conversation is being carried on between the active instruments. This I accomplish by providing the several branches leading from the terminals of the line with condensers whose individual capacities may be varied oradjusted, induction-coils the electric condition of whose secondaries may be changed by bringing in more or less turns, and receivers provided with double windings 5 5 capable of being worked in series or in multiple. By means of aswitch, hereinafter described, I am enabled to connect the independent windings of the said receiver in multiple or in series, the said switch simultane- 6o ously reducing or increasing the'oapacity of the condenser and the number of turns of the secondary coil in the inductorium in the ra= tio of, say, one to two or one to three, and thus changing the condition of the instrument both as to capacity and resistance, so that said instrument may be usedin the transmission of articulate speech with another instrument in which like conditions exist as to capacity and resistance, but with no other.

The active surface of the condenser, the number of turns in the secondary coil of the inductorium, and the windings of the receiver are proportioned in such a way as to cause the latter (the receiver) to respond only to a current of a certain tension and amperage. For instance, if the switch is in such a position as to connect the windings of the receiver in series and the entire surface of condenser and winding of the secondary in cir- 8o cuit a current, coming from a station in whose instruments like connections and conditions exist, will cause the receiver to respond, while a current emanating from a station in whose instruments different connections and conditions exist will leave the said receiver silent, or practically so. Thedrawings show a line or circuit to the ends of which three stations are connected. This is merely a representative illustration, and the number of stations at each end of the line maybe increased or decreased and still leave the system operative. I have shown only three stations in order to not complicate the draw ings or description; but it is evident'that any 5 reasonable number of stations can be thus connected to the ends of the line as long as provision is made to obtain this difference of capacity and resistance referred to above in the individual stations. The instruments at the ends of the line that are to be used in conversation must both be in the same condi- I will now describe the three conditions mentioned above. First condition: One-third of the condenser is in series with one-third of the secondary winding of the inductorium, which is in series with the coils of the receiver, which individually are connected in multiple and are collectively in series with the line. Second conditions Two-thirds of condenser is-in multiple, connected with twothirds of the windings of the inductorium, which windings are in series with each other and are connected in series to one-half of the winding of the receiver which is connected to the line. Third condition: All the three sections of the condenser in multiple are connected to the windings of the secondary coil of the inductorium which are individually in series and connected to both receiver-windings, which are in series and which are connected to the line. The other side of the condenser is permanently connected to the other branch of the line] In the accompanying drawings, Figure 1 shows the complete system,in this instance comprising three stations at each end of the line with the instruments in two of these stations at each end of the line shown in detail, while the other stations are represented in a conventional manner. This figure also represents intermediate stations in a conventional manner. Fig. 2 represents in detail one of the instruments and the circuit connections in the same. Fig. 3 is a plan View of the resetting device, circuit-closer, and also of the circuit-disconnector or circuit-breaker.

The arrangement of the line and the various stations are shown in Fig. 1. In this figure, Nos. 1 to 10 represent multiplexed long-distance stations.

I aim to make the working of the system entirely automatic, requiring only such operations or manipulations by the persons handling the instrument as are necessary in ordinary telephone practice and with which the public is thoroughly familiar.

I will now describe in detail the apparatus and its operation.

I can divide the apparatus into two distinct though correlated portionsnamely, the talking and the signaling apparatus. I will first describe that portion of. the apparatus which is used in the transmission of speech. This apparatus consists of a condenser A, an inductorium B, a contact-board O, a switch-sector vD, a gravity-hook E for suspending the receiver, a transmitter F, a receiver G, and a battery I-I. One side of the condenser A is permanently connected to one branch of the transmitting line, while the other side is subdivided into three parts of equal surface a a a These are connected to contact-sprin gs 1 2 3 on contact-board C.

1 The inductorium consists of an unbroken primary 1) and a secondary subdivided into three parts I) b 12 the ends of which are permanently connected to contact-springs 4, 5', 6, 7, 8, and 9 on the contact-board O.

The receiver G consists of a permanent magnet g, a diaphragm g, and two independ ent windings 9 The ends of these windings are permanently though flexibly connected to contact-springs 1O 11 12 13 of con tact-board O, the ends of the winding be ing connected with the said contact-springs 10 and 12, while the ends of the winding g are connected with the contact-sprin gs 11 and 13. The remaining contact-spring 14c is permanently connected to the other or, say, branch of the line.

The switch sector D consists of a plane surface of insulating material upon which metallic contact-strips d to (Z are secured. This sector-switch is arranged to swing on a pivot d and passes under the springs on the contact-board O in such a way that the strips d to d make metallic connection with some or all of the springs in certain positions of the said sector. The position of the sector as shown in the drawings is the normal or inactive one when the instrument is not in use, it being held in this position by the weight of the receiver, which is placed on the hook end 6 of the hook or switch E, counteracting the tension of coil-spring 6 The gravity-hook is fulcrumed at e, and an extension of it, e, acting upon the switch-sector, holds the latter suspended and out of contact with the spring-contacts when the receiver is on the hook. On releasing the gravity-hook by removing the receiver the switch-sector D will fall by gravity into one of the positions shown in the figure and marked I, II, and III. The exact position into which the segment will fall is governed by the lever I, the working of which will be described in connection with the signaling apparatus hereinafter. The primary or local. circuit is closed on the release of the gravity-hook through contact 6 transmitter F, line 15, primary 1) of inductorium B, line 16, battery H, line 17 18, fulcrum e, and lever E back to contact e The secondary or speaking circuit is closed in three different ways, depending uponthe position of the segmental switch D. We will first follow the path of the current, assuming the said switch to be in position I. The current coming from line through spring-contact 14, contact d into springs 12 and 13, respectively, in multiple,'through coils g and g of the receiver in multiple to springs 10 and 11 of board 0, thence to contact (1 by a wire located on the back of the board D, to contact 01 spring 5 to secondary coil 1) of inductorium, to contact-spring 4, to contact (F, to contact (i to contact-spring 1, to section a of condenser, and through condenser to line It will thus be seen that the two windings of the receiver in multiple are connected in series with one-third of the secondary winding of the inductorium B and one-third of the surface of the condenser. We will now follow the path of the current, assumingthe switch to be in position II, from line +-to spring 14, to contacts 01 d to spring 12, to winding g to spring 10,,to contacts (1 (1 to spring 7, to inductorium -winding b [0 spring 6, to contact d ,to spring 5,to inductorium-winding b, to spring 4, to contactd to 01 to springs 1 and 2 in multiple, to a and a in multiple, and through condenser to line It will thus be seen that only one winding of the receiver is in operation in series with two-thirds of the ind uctorium individually in series and with twothirds ofthe condenser in multiple. Lastly, we will trace the path of the current, assuming the switch to be in position III, from line to spring 14, to contact al to spring 13 through receiver-winding g to spring 11, to contact 01 to spring 12, through g to spring 10, through d to spring 9, through 5 to spring 8, through d" to spring 7, through 6 to spring 6,through @1 to spring 5,through b to spring 4, through d to springs 1,2,and 3 in multiple,to sections a a a of the condenser in multiple, and through condenser to line It will thus be seen that the two windings of the receiver individually in series are in series with the three windings of the inductorium individually in series and with the three sections of the condenser individually in multiple.

From what has been said it is evident that in order to establish conversation between any two stations it is necessary that the instruments of these two stations should be brought into the same condition as to the position of the switches D therein. This might be accomplished manually in a very simple way; by simply shifting the lever by hand; but the scope of usefulness of the device would not be so great, as it would necessitate some knowledge of the workings of the system on the part of the user. I therefore prefer to accomplish this end by means outside of the control of the operator, and I have illustrated and described these means in Figs. 1 and 2. This part of the device I operate in correlation with the signaling device,which I will now describe at length.

The signaling device may be, for convenience,divided into two correlated portions,the signaling device proper or the means for calling the distant subscribers attention to the instrument and a sympathizing device, by which I mean that part of the apparatus in tended to bring the two instruments into sympathy or into condition for exchanging articulate speech. As these two subdivisions of the apparatus are closely interrelated and interdependent in their working, it will be necessary to now and then refer to parts of one while describing the other.

The signaling device proper comprises a source of current, such as a generator K, operated manually or by power and for which. a battery may be substituted-a Morse key L, a signal-bell M, and a selector N.

I will first describe the apparatus and operation of the sympathizing device.

The sympathizer consists, essentially, of the two-armed lever I, the movements of which are controlled by and are dependent upon an electromagnetic setting device 0, a similar resetting device P, and frictionallypivoted levers Q and U, which latter are dependent for their operation upon Morse key L and an extension 6 of the gravity-hook E. The electromagnetic device 0 is dependent for its operation upon the condition of an electromagnetic obstructing device R, and both the device 0 and the electromagnetic obstructing device R, as well as the electromagnetic resetting device P, are controlled in a peculiar manner, hereinafter described, by the signaling apparatus and the gravityhook E. The two-armed lever I is normally held by the spring t in the position shown, Fig. 2. It has at its end a catch {2 to engage the retrogressing or disalined projections d 61 (Z of the switch, and it is rotatable about the fulcrum 6 The other end of the lever is provided with a segment having two sets of ratchet-teeth t 11 the inclined sides of one set of teeth extendingin the opposite direction from those of the other set of teeth at the opposite end of the segment. A blank space 2' is left between the two sets of teeth.

The electromagnetic setting device consists of a magnet 0, an armature o rotatable on a fixed fulcrum 0 and held in the normal position shown by the spring 0 The travel of the armature is limited by stops 0. The end of the armature lies just above the path of movement of the segment 2' clearing the latter in the normal position shown; but upon the movement of the armature, when the magnet 0 is energized, the end of the armature will engage a tooth on the sector and move the lever I.

The electromagnetic obstructing device R consists of the magnet r and an armature r rotatable about a fixed fulcrum r and held normally against a stop 1' by aspring 7". It will be seen that if armature r is attracted its end bears against or moves into the path of the end 0 of the armature-lever 0 and renders the device 0 inoperative.

The electromagnetic resetting device P consists of an electromagnet 19, an armature p rotatable about a fixed rulcrum p and held in normal position against stop 19 by spring 19 This armature-lever is provided with escapement-pallets p 19", so arranged that on every oscillation of the armature-lever it allows the lever I to travel one tooth in the direction of the arrow under the tension of the springz". It will thus be seen that the resetting device P operates in the opposite sense to that of the setting device 0, causing movement of the segment to the left in Fig. 2, while the device 0 causes movement of said segment to the right, and further on the purpose of this will be fully explained.

The bell-crank lever Q is frictionally mounted upon a fulcrum q and is provided with a catch 1 so arranged as to upon its depres-- sion engage the teeth i 01 sector i This depression takes place as soon as the Morse key L is depressed, and the lever stays in that position, owing to the frictional restraint at its pivot exerted by the spring'q If, however, the gravity-hook E should be released from its normal position, the end a of the extension 6 thereof will engage the arm g of the bell-crank locking-lever Q and restore the same to the normal position. (Shown in Fig. 2.) Another arm q of the locking-lever travels in the path of a circuit-breaker consisting oflever U. The arm is operated at times-in such a way as to cause the said lever to assume the position shown in dotted lines in the drawings. This lever, like the locking-lever, is frictionally held on its pivot at u. The contact a is provided, normally establishing metallic connection between the contact-plate t and fulcrum it. This contact, however, is broken upon the depression of the Morse key through arm q of the locking-lever Q and remains so until the pin t of lever t, Figs. 2 and 3, restores it to its normal position. The construction and working of the lever 75 will be explained under its proper heading, and it need only be said here that the depression of the Morse key at the calling station operates through the lockinglever Q to break a contact at 1B, which contact renders the local resetting device P inoperative, and it also prevents the sending out of a resetting impulse from the said calling station, which would aifect all the instruments, and the purpose of this is to prevent the resetting device from operating more than once during the entire series of operations necessary to carry on a conversation. In other words, the task of resetting the instruments is assigned to the called station only in each instance, and likewise the task of setting the instruments is in each instance allotted to the calling station. The object of the circuit-breakerUis to prevent the resetting device from receiving two impulses should the receivers at the calling and called stations be hung up in succession. This would result in two movements of the resetting device, and it would move the lever I resetting action will be referred to more at length hereinafter.

From the foregoing description it will be seen that if a current is caused to pass through electromagnet 0 of the setting device this latter would, through the agency of armature 0 move segment 13 one tooth. On the cessation of the current the saidsegment would stay in this new position, being retained therein bypallet p of the device P. If another impulse of current should be sent in a like manner through the magnet o, it would result in moving the segment another tooth ahead, and so on. Should, however, the electromagnet r of the obstructing device be energized before or at the moment the magnet 0 receives current, then the armature of the latter would not operate and no change would take place in the position of the segment. This would also hold true in case the Morse key L was depressed while magnet 0 received current, the locking-catch c in this case preventing movement of the segment 2' Now supposing the segment to have been moved one or more teeth, it will be seen that upon the magnet p being energized and demagnetized the action of the armature p and the pallets p and 13 will result in returning the Segment 2' the space of one tooth in the direction of the arrow under the tension of the spring for each such magnetization and demagnetization of the coil 19. We will show, after describing the balanceof the apparatus contained in this system, how these different operations and the resulting conditions of the lever I are brought about by the signaling device and ultimately by the operator in handling the receiver.

It will be understood that at each station there is a switch D and the described parts cooperating therewith, these parts including an electromagnetic device 0 for setting the lover I in position relatively to the switch, an electromagnetic device, as the magnet and armature r and T for preventing the electromagnetic device 0 from operating and setting the controlling or selecting lever I, a device, as the detent-lever Q, for preventing the said electromagnetic device 0 from operating the lever I under certain conditions, and an electromagnetic restoring device P, through which the selecting-lever I is permitted to return to normal position upon the conversation having been brought to an end.

It will further be understood from the foregoing and the explanation of the wiring, hereinafter described, that the devices 0 and P are respectively affected simultaneously in all the stations during and through the act of calling one particular station and the hanging up of the receivers, while the devices R and Q, respectively, are of a selective nature, which means to say that they affect the position of lever I only in the calling and called stations by rendering the setting device 0 inoperative in each of the said stations. In the way of explanation we may say here that the lever Q locks lever I in the calling station, while the device It performs in effect the same office in the called one, thereby bringing about in these two stations a position of the segmentswitches D differing from the position of this switch in all the other stations in the circuit, thus fulfilling for the two first-mentioned stations and for those only the requirements for the transmission of articulate speech. In other words, in the calling and called stations the selecting-levers I of the switches D are maintained in their normal positions by the respective actions of the loeking-detent Q and the obstructing device R. It will be shown, further, that the remaining stations can likewise, in pairs, bring about the same operative condition relative to the stations of each pair without in the least affecting the adjustment or condition of the two stations first entering into conversation, the conditions between eachintercommunicating pair of stations being different from those between the stations of all the other pairs. Finally,it will be shown how the act of hanging up the receivers will restore the apparatus step by step to its normal position of rest as such act is performed successively by the various pairs of talkingstations.

From the foregoing it will be understood that the instruments in the various stations are adjustable as to their ability to send and select voice-currents on the line, and like adjustments exist in intercommunicating stations and unlike adjustments between these and all others in the system.

The signaling device consists of a Morse key L, normally held against a contact Z by a spring Z and provided with a working contact Z This key is fulcrumed at 5 There is also provided a solenoid n, which through a soft-iron core 71 operates a three-armed lever n fulcrumed on a fixed pivot 77 in a manner shown hereinafter. The lever n carries pivotally on one of its arms at n a ratchetpawl n, which has on its extension a pivot n upon which an auxiliary lever 02 is fulcrumed. The normal position of the lever 01 is maintained by the spring a". One arm of the lever carries a pivotally-connected latch n projecting into the path of one of the arms of a bell-crank lever 12., but clearing the latter at or near the end of its stroke or extreme working position. Lever n swings on a fixed pivot n and carries at its extreme end at a pivotally-connected rack-sector 71 which, moving in the arrow direction, slides over the teeth of the pinion n of a retarding device, preferably a fan a while when the said lever moves in the opposite direction, impelled by spring it, its motion is retarded by the said rack engaging the pinion 11. and thereby operating the retarding device. At an intermediate point on this arm of the lever a connecting-rod n is arranged, and this operates a double-armed lever n, f ulcrumed at n and bearing at its opposite end a smooth circular are 72 against the surface of which the catch 11 of the lever a normally impinges. This smooth arc edge is provided with an offset at n at its extreme end, the office of which will be explained farther on. There are also provided a fixed contact 01 and two slightlyyielding contacts @1 H In the normal position of the lever a an electrical connection is established betweemcontact 77, and the said lever, and likewise between the contacts 72 01 through the medium of the metallic plate at, rigidly connected to and insulated from the lever n. It must be remarked here that in the operation of the device this con tact n is established slightly before that of n and the lever, for purposes set forth farther on. The lever 11 also establishes metallic contact between parts thereof and the contacts 91 72 when the magnet 02. is energized. Here again it will be noticed that contact n is established slightly ahead of the contact n and maintained slightly longer than contact 92 The devices just described act upon a circuit-selector S in a manner hereinafter described. This selector consists of a sector 8, having teeth and normally held in position shown by a spiral spring 5 The ratchetwheel or sector carries a contact-arm 8 capable of establishing electrical connection between the said wheel and one of aseries of contact-buttons 3 There may be as many of these contact-buttons in every instrument as there are stations on the multiplex line. Only one, however, of these contact-points and a different one in each station is electrically connected to the balance of the apparatus or system. A pawl s is also pro vided, holding the wheel in the position brought about by the action of the lever 41. and against the tension of the spring 3 Should, however, the pawl n be lifted out of engagement with the ratchet-wheel it would impinge against a projection s of the pawl 8 disengaging the latter from the wheel also and allowing the wheel to return to normal position. The wheels carries another projection the end of which normally rests against one of the prongs of the lever a and thereby would prevent the catch 01 of the said lever engaging the recess 11 of the lever it even should the latter be in such a position as to allow such an engagement.

Dependent upon and interrelated with the devices just described is a device T, intended for the operation of the aforementioned device P and itself dependent upon the operation of the gravity-hook E.

To the extension-arm e is fastened an insulating-segment 15', carrying two metallic contact-plates t t and a contact-plate #hFigs. 2 and 4. These contacts t t are insulated from each other. Contactpoints t t t t are so arranged that upon the lever e movingin the direction of the arrow indicated a momentary connection will be established between 15 t, 25 and 25 respectively, through the contact-plates t 15 while on the lever moving in the opposite direction such will not be the case, the contact-plates in this case clearing the fixed contacts. This is accomplished in the following manner: The contact-points t t, t and t are fastened to a lever 25 capable of oscillating on a fulcrum t and pressed by the spring 25 toward the segment i to con IIO v tact with the plates t i A lateral extension is provided on this lever. The inclined sides of the projection are capable of engaging the inwardly-projecting pin i on the le ver 1, pivoted to the segment i and held in theposition shown against a stop t by a spring 75 It will be seen that if the lever c moves in a direction opposite to that of the arrow the pin i will pass under the projection thereby moving the contact-lever Z away from the segment i, dropping the latter into position again, however, at the end of the stroke; but if the lever moves in the direction of the arrow, then pin i passes up and over the projection 29 thereby leaving the contact-pieces t t t and i in position to contact with the plates t respectively. It is understood that in both extreme positions of the gravity-hook E all the contacts are open and that only during the movement of the lever in one specified direction a momentary contact is made.

Before describing the operation of the signaling device I may state that it is proposed to assign a certain call-number to each of the stations, as is done in common practice. Again, as in common practice, the signal to which each station is supposed to respond consists of such a number of impulses sent over the line as corresponds to the number of the station wanted. Station 1 would therefore be called by one impulse, station 2 by two, and so on. For the operation of this system i it is essential that the last impulse of theseries should be of longer duration than either of the preceding ones. This again conforms to the common practice. I repeat here that the apparatus is designed with a view to make its handling by inexperienced persons possible and safe. I will now proceed to describe the operation of calling and the phenomena taking place in, first, the calling station, then in the called one, and then in all the others in the multiplex line.

Actions and conditions in the calling stat'ion.Let us suppose the calling station to be station No. 1 and that wanted to be station N0. 4. The operation to be gone through by the caller would therefore consist in getting his generator K into working condition and then depressing the Morse key L four times in succession, letting the last depression last longer than the three preceding ones. The action for depressing the key for the first time would cause a current to flow from the pole of the generator through line 20, contact I, key L, pivot Z line 21, solenoid a, line 22, line 23 to long-distance line to all outside instruments, through these instruments in multiple, as explained farther on, to earth, from earth to line 24, back to pole of generator. We will now see what has taken place in the signaling and sympathizing device of the station thus calling. The depression of the Morse key L has caused the lever Q to descend into engagement with the segment 1%. It has also caused through the agency of the said lever Q the breaking of the contact a by moving lever U into the position shown in dotted lines. Further, it causes the energizing of the solenoid n, which causes the attraction of the core a and the consequent movement of the lever a It has also caused through the latch n the movement of the lever n to its extreme upper position, and in the last part of its movement the lever 11, leaves the lever n free to return to its normal position of rest in a period govern ed by the retarding device n Referring again to the lever 71 we see that the pawl n has moved the wheels one tooth ahead. The impulse, as explained above,being a short one, the current will be broken and the lever a be returned to normal position before lever a under the influence of the retarding device, has returned to its normal position. The only permanent change having taken place therefore consists in the wheel 8 being moved one tooth ahead. Farther on we will show that this short impulse, as well as all others that may be sent, affects all stations on the line in the same manner. If now the key L be depressed again for a short impulse, the same action will take place and the wheel 8 will be moved another tooth ahead. This is repeated on the third impulse. Upon the fourth depression of the key, which is of longer duration, the same action again takes place, and, in addition thereto, one which we will presently describe. In this latter instance the lever 11 will have reached its extreme position of rest, as shown in the drawings, while still the lever n is in its extreme working position. This closes a local circuit in the calling station in the following manner: from pole of battery I-I through line 25, pivot n lever at, contact n line 26, pivot a, contact n line 27, magnet 0, line 28, line 29 to pole of the battery. This causes the magnet 0 to be energized and attract its armature; but owing to the fact that the catch (1 has engaged the first of the teeth 71 the armature o is unable to move the segment i, and no permanent change of any character at all takes place until the release of the Morse key L. At that moment lever 01. returns to its position of rest. Now as the catch n has engaged in this particular instance the recess n of the lever 72 the pivot 17, becomes a fixed fulcrum. Therefore when the lever 01 returns to such normal position it exerts an upward pull upon the fulcrum a, which has the effect of disengaging the pawl Whom the teeth of the Wheel .9. This pawl 97. in turn lifts the detent 3 out of the wheel 3', which wheel is therefore free to return to the position shown under the action of the spring 3 When the wheel is nearing the end of its travel, the lever 3? disengages the catch 11 of the lever 41. from the recess 72 with the effect of return ing the pawls n 5 into engagement with the wheel .9, ready for another action. In other words, upon the calling operation being completely over the entire signaling mechanism is in the same position again as it was before said calling took place. We have therefore a condition of the entire apparatus corresponding with that shown in Fig. 2, with the exception of levers Q and U, which are in the position shown in dotted lines. The condition of the apparatus in this calling station immediately before the cessation of the long impulse is shown in station 1, Fig. 1. If now the receiver be taken oif the hook (2 the gravity-switch E will be released and as sume at once its working position, as shown in dotted lines, the extension a simultaneously restoring the bell-crank locking-lever Q to the position shown in the drawings. No contact will be made in the contact device T, as previously explained. The segment-switch 1), being now released by the withdrawal of the end e of the receiver-hook, will fall into the position III, being held there by the catch 1' arresting said descent by engaging the projection (Z local primary circuit of the transmitter F will be closed in the following manner: from the pole of the battery H through line 17 18,

. fulcrum e, lever E, contact e microphone F,

line 15, primary 1) of inductorium B, line 16 to pole of battery H.

Referring back to the operation of the parts whereby the pawl n and detent are released from the wheels only after the requisite number of impulses have been given, it will be noticed that the three short impulses are given before the retarded lever 71 has returned to normal position, and consequently during these impulses the lever 91 is in its moved position, it being actuated by the lever a, and consequently the notch 12 has been moved out of the path of the catch a on the levern controlling the throwing out of the pawl n and the detent 5 As soon, however, as the lever 91 is returned to normal position the lever 02 in following the movement thereof has brought its notch into the range of movement of the catdh 01 so that the said catch will engage the notch when the lever 71 is operated by the solenoid, and then upon the return of the lever m the catch it being a fixed point, there occurs a straightening out of the points 12 111 and n, and this has the effect of rocking the pawllever 41 on its pivot, throwing the same out of the teeth of the wheel .9 and throwing out of operation also detent .9 so that said wheel can return to normal position.

In will be seen from the above that the calling instrument has its talking apparatus and circuits arranged so that it can enter into conversation with another distant instrument in which the same conditions prevail. How these conditions are brought about in said distant or called station will be explained later.

Upon" the operator at the calling station completing the conversation and hanging up his receiver the only permanent result which At the same time the is effected is the breaking of the local microphone-circuit.

As before stated, the task of resetting the instrument to normal position falls upon the called station, and the resetting action results from the operator at the called station hanging up his receiver, and thus closing a resettingcircuit to all the instruments. We will briefly state at this point, however, why the hanging up of the receiver at the calling station has no elfect in starting a resettingcurrent to flow. YVhen the calling operator depressed the key L to make his signal, the contact a was broken, and as this contact controls the resetting-currentemanating from the battery H of the calling station it will be seen that the hanging up of the calling receiver will not close this circuit, in spite of the fact that the movement of the circuitcloser T resulting from the hanging up of the receiver closes the contact at because this contact is not closed until the final movement of the closer T, and at this time the contacts t i are not engaging the contact-plate 25 which they must do in order to fully establish the resetting-circuit. This will be made clear in connection with the description of the actions in the called station which now follows.

Conditions in the called station-In the called station the phenomena taking place during and as a result of the three short impulses sent from the calling station are identical with the ones just described with reference to the calling station. Briefly stated, the solenoid it in the called station is energized in succession and the lever n turns the selecting-wheel step by step. The lever 11 has also set in motion the lever a which is now returning to normal position with a retarded movement. The current arrives at the solenoid n of the called station through lines 23 22, and after passing through the solenoid n it returns to the first station by way of line 21, key L, contact Z, and line 24 to ground, and thence by wire 24 at the calling station from ground to the pole of the generator. Upon the long or fourth impulse being sent the called wheels will have advanced so far as to bring its contact-arm 5 into electrical connection with that one of the contact-points s which in this instance is connected to the balance of the apparatus or system, as previously referred to and as shown by dotted lines in Fig. 2 and in station No. 4, Fig. 1. When the levern now returns to near its normal position, while still lever n is in its working position, a local circuit is established as follows: from the +pole of battery H through lines 17 and 25, lever a, contact 17/ line 26, fulcrum n, contact 72 line 36, contact 72 plate 02 contact n line 37, wheel 3', arm 8 contact 5, line 38, bell M, line 39, magnet r, lines 40 and 29 to pole of battery. Immediately after the establishment of this circuit another, shunted circuit is established from pole of battery, line 25,

fulcrum n lever n contact n line 26, f ulcrum n contact n line 27, magnet 0', lines 28 and 29 to pole of the battery. This latter circuit would energize magneto and cause the latter to attract its armature 0 and thereby move the sector 2' one tooth ahead were it not for the interposition of the obstructingarmature r of the previously-energized magnet r into the path of arm 0 of the said armature o". It will therefore be seen that during the period in which magnet r is energized the armature 0 cannot move. Upon the cessation of the impulse sent from the distant station lever n returns to its normal position, opening first the circuit in which the settingmagnet 0 is included and immediately afterward the other circuit. It will therefore be seen that the device 0 does not operate at all. The cessation of the impulse sent from the distant calling station has the further effect of restoring the entire signaling apparatus to the condition shown in the drawings in the manner explained in connection with the calling station, said action including the throwing out of the pawl and detent when the lever n returns to normal position after the long impulse has been given. Now, as during the maintenance of the circuit in which magnet r is included the bell M was ringing, the manner in which the operators attention at the called station is roused is clearly shown. The operation now following in the called station-namely, the removing of the receiver from the hook and its replacing after the couversationresults in the following phenomena taking place: Upon taking the receiver off the hook the segment-switch D drops into position identical with that of the switch D at the calling station in the manner explained. The contact device T remains inoperative, as previously explained. When now the receiver is replaced after the termination ofthe conversation, the segmentswitch D is returned to its position of rest, and the contact device T momentarily closes and opens again a circuit as follows: from pole of battery I-I through line 17, contact u of, line 30, contacts i 25 77, line 31 to longdistance line to the distant stations, includ ing the calling one. The path of the circuit in these stations is as follows: from long-distance line to line 31, to bridge-contacts 15 15 Z or 25 15 according to the position of gravitylever E, to line 51, to line 33, to magnet 19 to ground, from ground to line 32 in the called station, through magnet 19 to line 33, to contact 25W 15, line 34, to pole of battery H. The energizing of magnet 19 has caused the latter to momentarily attract and release its armature 19 but as the lever I in this particular station2'. e., the called oneis at that time in its extreme position of rest it has had no effect upon the latter. Farther on it will be shown, however, that the act of hanging up the receiver has performed a very necessary office in the other stations. It will be seen that during the conversation or from the moment when the hook E is released the called station has its segmental switch D in the same position-viz. position III-as the callingstation-via, position Ill-and conversation can therefore take place between these stations, because in these two stations the instruments have like adjustments as to their ability to send and select voice-currents.

Conditions and actions in stations not wanted.We will now consider what takes place in all stations on the line outside of the call-- The sector 2' one tooth ahead against the tension of the spring 11. The obstructing devices are not active at this time, because at the fourth impulse the arms 5 in the stations not wanted will not be making contact with their appropriate contacts, and when n has returned to normal position the arm 8 will either have passed or not yet arrived at the appropriate button and there will be no action of the 0bstructors in the not-wanted stations when their setting-magnets are energized. Upon the cessation of the long impulse sent from the distant station the wheels 8 return to their normal positions in the way previously shown. The armature o is released when the solenoid-lever returns to normalposition; but the lever I and segment i are held in the new position by pallet 19 and will be so held until an impulse of current are sent through the magnet 19, which happens when the parties engaged in the conversation hang up their receivers, as previously described. The status or condition of the stations on the line while conversation is still going on between the first two stations is therefore as follows: The levers I in the first two mentioned stations are held in their normal position owing to the action of the locking-lever IIO IIS

Q at the calling station and to the action of the ohstructor R at the called station, and the segment-switches D of these two stations have dropped into position III, owing to the removal of their receivers and the fact that the levers I remain in normal position. The levers I in all the other stations are in a position one tooth ahead of the normal one, owing to the fact that in all these stations, the contact-arm s not having synchronized, in closing the circuit to the obstructor R with the closing of the contacts n and n controlling the circuit to the setting devices 0, the said devices 0 were free to operate and were actuated by the operator at the first station calling the one at the fourth. If now while the above-mentioned conversation is going on another party desires to establish communication from one of the idle stations lows: He would give four short impulses,

followed by a long one by means of the Morse key L and generator K. The short impulses would cause the selector-wheels s in all stations busy and idle to be advanced four teeth, while the long impulse in all the stations would have the efifect of moving the wheels 5 still another tooth and energizing the magnets 0 in all the stations, and upon its cessation it would have the effect also of returning the wheels 8 in all selectors to the normal position in a manner previously described. Besides this distinct and different conditions would have been brought about in the busy stations as well as in the idle ones, as will be presentlyexplained. In the busy stations Nos. 1 and 4 the energizing of the magnets 0 would have caused these to attract their respective armatures 0 but as in both these stations the catch t abuts against the surface of the sector-switch D, which in both of these stationsis in position III, the said armature o is unable to move the levers I, and no change whatever takes place in the condition of these two stations.

Condition in calling statton N0. 2.-We will now see what takes place in the calling station No. 2, always supposing the two first stations are continuing their conversation. The lever I of this station, as before stated, has advanced one tooth by the previous switcl1ing-t.e., when the first call was made from station No. 1 to station No. 4. The depression of the key in this station No. 2 has caused the descent of the detent-lever Q into the second tooth of the series 2', thus preventing the further movement of the said lever I under the influence of the armature 0 in spite of the fact that the magnet o is energized in this station No. 2 by the said long impulses. At thesame time the contact n a is broken. These are the only permanent changes which take place in the calling station No. 2.

Conditions in called station No. 5.In the called station No. 5 the long impulse from station No. 2 has caused, as in the first instance it did in station No. 4, the establishment of two circuits within the said station,

setting into action the magneto and the obstructing device R. Thisprevents the'setting deviceO from operating. The bell ll/Lthough,

is set in operation, giving an audible signal. N o permanent change, however, has taken place in this station, and the lever I remains in the position before mentioned-that is, one tooth ahead of its normal position, to which it .was movedwhen the call was sent from station No. 1 to station N o. 4. The same relative position of the lover I in the two stations Nos. 2 and 5 now existthat is, both the levers I in these stations have been advanced one tooth, in which respect they differ from the busy stations Nos. 1 and 4, and if now the receivers of these two stations were removed fromtheir hooks the switches D would .fall into the position II, being each arrested by the lever I, and thus the switches D would es tablish connections in these two stations between the inductorium, condenser, and receiver entirely different from those existing between said parts in stations Nos.1 and 4and stations Nos. 2 and 5 could talk entirely independent of stations Nos. 1 and 4.

Conditions in the stations not wanted-to w it, Nos. 3 and 6.-In the stations Nos. 3 and 6 the short impulses have brought about identical conditions with those in the stations just mentioned. The long impulse now coming establishes a local circuit in all of these stations, whereby magnet o is energized and upon the cessation of the long impulse has restored the signaling devices of these stations Nos. 3 and 6 to normal position. The energizing of the magnet 0 has caused its armature to be attracted,which moved the segment 1 still another tooth ahead in both Nos. 3 and 6 stations, where it is held by pallet 19. To .sum up,we have at the end of this signal between Nos. 2 and 5 the following conditions as regards levers I: In stations Nos. 1 and 4 (now talking)levers I are in their normal positions, as shown in Fig. 2, and they are holding the switches D in position III. In stations Nos. 2 and 5 levers I are one tooth ahead and in stations Nos. 3 and 6 two teeth ahead of normal position. If now the second pair of partiesnamely, stations Nos. 2 and 5 take off their receivers to engage in conversation,their respective segment-switches D simultaneously drop into position II. In this position they are held by the catches t of levers I, and it is evident that these stations can at once enter into conversation notwithstanding the fact that the previously-switched stations Nos. 1 and 4 have not yet terminated theirs.

In order to fully and minutely explain the workings of this system under all conditions, it will be necessary to subdivide this explanation, with the following points in View:

First condition. The stations Nos. 3 and 6,

enter into conversation while the two other pairs of stations are still engaged.

Second condition. The first switched sta tions Nos. 1 and 4 terminate their conversation, 2 and 5 continue, and 3 and 6 enter into conversation.

Third condition. 2 and 5 terminate, 1 and 4 continue, and 3 and 6 enter into conversation.

Taking up the first condition, the act of signaling from station No. 3 to station No. 6 would operate bell-crank lever Q in station No. 3 and break the contact me in the same station. In station No. 6 it would ring the no permanent effect at all.

bell without otherwise affecting its mechanism. In stations 1, 2, 4, and 5 it would have If now the operators at Nos. 3 and 6 take off their receivers, the segment-switches in the stations would drop into position I. We would then have the following conditions as concerns the switches D in all the instruments: In Nos. 1 and 4 segments D would be in position III; in Nos. 2 and 5 they would be in position II, and in Nos. 3 and 6 they would be in position I, and itis evident, therefore, that all three sets of stations can simultaneously and independently carry on conversation. Now suppose stations Nos. 1 and 4 terminate their conversation the following will result: In these two stations the segment=switches D would be returned to normal position by simply hanging up the receivers, the levers I, being in normal position already, would not be affected,

and in station No. 1 the contact to 10 would be restored by the action of pin :9 In the balance of the stations the impulse sent by the contact device T through the action of the operator at called station No. 4 hanging up his receiver would cause the magnet 19" to attract its armature p and immediately release the same. This would cause the return of the lever I in the direction toward its normal position for the space of one tooth and the consequent dropping of the segment-switches D for the space of one tooth-in other words,

the switches at stations Nos. 2 and 5 would; drop from posit-ion II to position III and they switches at Nos. 3 and 6 would drop from position I to position II. Though now differently connected these stations can still in pairs continue to converse, as their segmentswitches D of each pair are still relatively in identical positions, though the position of those of one pair is different from those of the other. If now stations Nos. 2 and 5 should hang up their receivers, their segmentswitches would be returned to normal position and the levers I in Nos. 3 and 6 would return to normal, thereby dropping the segment-switches D at stations Nos. 3 and 6 into position III. If now these two stations also terminate their conversation, the entire apparatus of all stations would be returned to normal.

It will be seen from the above that when the signal is sent between the first pair of stations, whether Nos. 1 and 4 or any other pair, the selecting-levers I of said stations will remain in normal position in line with notches d of the switchesD in said stations, while at the same time the selecting-levers I in all the other stations will be moved one tooth or one step toward their respective switches D. When the receivers of the first pair of stationsfor instance, Nos. 1 and 4 are removed from their hooks, the switches D in said stations will fall to position III, where they will be held by their levers I-, thus establishinga certain and like condition of capacity and resistance in these stations. When now a signal is sent between a second pair of stationsfor instance, Nos. 2 and 5the levers I of these stations will be prevented from moving from their present position, which is now one step toward their switches D from normal position, but at the same time the le vers I of the idle stationst'. 6., Nos. 3 and 6-will be moved another step toward their switches D. In the first pair of stations no change will take place, as their levers I are bearing against their switches D. When the parties at the second pair of stations 2 and 5 take down their receivers, the switches D in 1 said stations will fall and be arrested by their levers I in position II, and thus a condition of capacity and resistance will be established in this pair of stations entirely different from that existing in the first pair of stations, whose switches are in position III. This condition, it will be clear, is made to exist as soon as the second pair of stations are placed in communication. Now when a signal is sent between the third pair of stationsfor instance, Nos. 3 and 6--the levers I of these stations will be maintained in the positions to which they were moved by the previous signaling operationz'. 6., two steps toward the switches D- while in both of the other pairs of stations no change will result, as the levers I of these stations are bearing on the edge of their switches D, and the action of the armatures 0 will be ineffective. When the receivers of this third pair of stations are removed from their hooks, the switches D of these stations will drop and engage the levers I in position I, and a condition of capacity and resistance will be established in this pair of stations (littering from the conditions in each of the other pairs of stations, and articulate speech may be transmitted between the stations of each pair simultaneously with the transmission between the stations of each of the other pairs. Now if the first pair of stations cease talking and their receivers are hung up the resetting devices I in all the stations throughout the system will be given one impulse (the circuit-breaker U of the calling station of the first pair preventing more than one impulse) and the levers I in the second and third pairs of stations will be moved one step to the right in Fig. 2 or in a direction away from their switches D, and consequently the switches in the second pair of stations will drop from posi tion II to III, while those in the third pair of stations will drop from position I to II, it being understood that the switchesin the first pair of stations are returned to their uppermost or inactive position by hanging up the receivers, and the levers I of the first pair of stations are not moved toward the right, for, as before stated, they are not moved from normal position when communication is established between the two stations of the first pair. When the receivers of the second pair are hung up,a similar action to that described takes place, all the resetting devices P in the various stations being given one impulse from the hanging up of the called-stations receiver. The levers I of the first and second pairs are already in normal position, so that the only effect is to move the levers I of the third pair of stations Nos. 3 and 6 another step to the right and back to normal position, in which action the switches D of the third pair of stations fall to position III. The switches of the second and first pairs of stations are now all the way up or in inactive position. Conversation can still be had between the stations of the third pair,and when their receivers are hung up the switches D will all be in inactive position, and the whole system will then be reset for a new se ries of operations.

It will be understood that when the receivers in a pair of stations are hung up the displaced levers I move one step to the right and the switches D fall; but the relative difference in position between the different pairs of switches is maintained, and therefore the relative difference in capacity and resistance between the diiferent pairs of instruments is maintained also.

Gall mg abusy station. -Supposin g the operator at station No. 3 attempts to call up station No. 2, not being aware of the fact that this station is busy, as well as, for instance, Nos. 1, 4, and 5, the following would take place: The long impulse of his signal would notify by bellM the then-talking station N01 2, without, however, effecting any changein this station, as well as in all others, the switches D and levers I of which are locked. His own instrument would therefore have its switch D in such a position as to differ from that of all the other instruments, and it would be impossible for him to communicate with any of the busy stations. The fact that his receiver remains silent after such a call would serve to notify him that the station he wanted was busy.

Considering the second condition, the termination of the conversation between the stations 1 and 4, while 2 and 5 continue, results in the following change taking place: The hanging up of the receiver at station 4 causes all the magnets 55) in all the stations to be momentarily energized, thus operating levers 19 This has no effect upon the levers I in stations 1 and 4, they being in the normal position already. The levers I in 2 and 5, however, are thereby returned to normal and the switches D at each station are dropped to position III, while the levers I at stations Nos. 3 and 6 are returned the space of one tooth toward normal position, thereby leaving them one tooth removed from the said normal position. If now station No. 3 should call up station No. 6 and upon the signal being given these stations should remove their receivers, then the respective switches D would drop into position II and conversation could ensue at once, as the stations previouslyengaged-namely,Nos. 2 and 5--have changed their switches from position 11 to III. If now, 2 and 5 should terminate their conversation, this will result in dropping the switches in Nos. 3 and 6 from position II to position III. When finally the last two mentioned pair of stations 3 and 6 terminate their conversation, the entire apparatus of the system will be returned to its normal position. The condition 3 is identical, stations 1 and 4 and 2 and 5, respectively, changing places.

It will be understood by one skilled in the art that any desired combination may be secured. 1

From the foregoingit will be seen that when a signal is sent between two stations the instruments in these stations will be held in the position they occupy at the time of sending, while in all other stations certain alterations or adjustments will take place in the mechanism, and these alterations or adjustments will be rendered effective in changing the conditions of capacity and resistance in the pair of instruments next used relatively to the first two instruments whenever the re ceivers in the second pair of instruments are taken down. The same relative action takes place between the second and third pairs of stations when a signal is sent between the sta tions of the second pair as between the first and second pairs of stations-that is, the instrumentsin the second pair ofstations are not altered by reason of the signaling; but certain alterations take place in the stations of the third pair, which alterations produce a change of the conditions in these instruments as to capacity and resistance when the receivers thereof are taken down. In the reverse aotionof the system-2'. e., when the pairs of stations in succession cease talkingthe mechanism of the system is restored step by step to its normal position of rest. The levers I return step by step, andwhile the conditions as to capacity and resistance change in each communicating station by reason of the step-by-step restoration in the mechanism the relative difference in the conditions as between pairs of stations is maintained in all those instruments which are in the talking-circuit.

From the foregoing description it will be clear that the receivers are adjustable as to their electrical conditions by reason of the employment of the two coils g 91 It will be understood, however, that I do not limit myself to a receiver of this character, as any other form of receiver would answer the purpose, so long-as it is capable of at one time presenting one electrical condition and at another time another. This might be brought about by a receiver which is composed of a series of instruments, each being like an ordinary receiver, butwhosewindings differ from each other. This receiver would then be of composite form, and in practice the operator would at one time use one of the instruments and at another time he would use another instrument, according to the conditions existing in the system, and

preferably automatic means would be provided by which the operator could take down only that instrument the electrical condition of which sympathized with the instrument at the intercommunicatin g station, though such automatic means would not be absolutely necessary. Such a receiver is within the scope of my invention, and when I refer to a receiver adjustable as to its electrical condition. I mean the one previously described or the one now referred to or any other in which the electrical conditions are different at different times, whether by adjustment, substitution, or otherwise. I prefer, however, for reasons of simplicity to use the receiver shown and described.

The instruments in the stations, it will be understood from the foregoing, are adjustable as to their ability to send and select voice-currents. The means for controlling the adjustment of the instruments comprise the switch D and the lever I, and these are in turn controlled by the signaling and selecting means through the medium of the sympathizing mechanism and by the manipulation of the receivers.

While I prefer to use the combination of the condenser, inductorium, and receiver described'as the means for varying the electrical conditions in the instrument, I do not wish to limit myself to this combination.

It will be understood that while I show and describe the magnet P and solenoid n as connected in the system to be energized by a current passing over the line it is clear that these parts may be energized through suitable local batteries and relays; but as such features are of common practice it is not necessary to show or particularly describe the same herein.

I am aware of Letters Patent of the United States granted to IIutin and Leblanc, No. 522,564, dated July 3, 1894, and No. 628,246, dated July 4, 1899.

My system described fundamentally differs from any now known in that the individual stations comprising it are of identical construction and arrangement. The selective element or character enters into the system only, and the identical arrangement of the parts ceases only when a user or operator commencesaconversation. All apparatus of this class now known contains in each station parts and elements differing permanently in arrangement and performance from the parts in each of the other stations, and it is this permanent difference as between the apparatus in the several stations upon which the operativeness of all these known systems is dependent. It is therefore evident that in multiplexlpractice a substation of the group of stations at one end of the line can only communicate with one particular substation of the group at the other end of the line-21. e., the one having an identical arrangement of elements with the substation first mentioned. Now as in all the systems referred to this arrangement of parts is fixed, communication between other stations than-the pairs identical in an arrangement is an impossibility.

My system, while as simple of operation as the commercial apparatus now in use and while not requiring any skill or knowledge of the apparatus on the part of the operator, automatically performs all the operations and adjustments in the apparatus necessary to bring any one station of the group at one end of the line into telephonic communication with any station of the group at the other end of the line and any additional stations atone end of the line with any idle stations at the other end of the line. The changes or adj ustments of a mechanical and electrical nature in all the stations of my multiplex sys tem are performed by the apparatus itself and always in groups of two, each pair, as it were, preempting one of the multiplicity of conditions of speech of which the system is capable in the order of the time of the calls until the limit of the system is reached or as long as any idle stations remain. Naturally, however, the number of stations available for conversation decreases as the number of talking pairs increases; but as long as the capacity of the system is not fully taxed idle stations may enter into conversation.

As manual operations, or operations depending upon the intelligence of the user, are eliminated from my system to the greatest possible extent, itis evident that its functions must be reliable. The only manual operations are, first, the indication of the number of the station desired by giving a predetermined signal consisting of a series of impulses, the number of which may correspond to the number of the stations wanted, and, second, removing the receivers from their hooks, whereupon conversation can at once begin. Provision is also made, as described,

whereby the operator is notified when he hascalled a busy station. At the termination of the conversation the only operation necessary is to hang up the receiver. The manner and operation of setting of the parts, as well as the resetting of the apparatus, is entirely beyond the control of the operator. Accidents to any single instrument or instruments will be confined to these and will not affect the balance of the apparatus.

Wherever in the specification and claims hereof the term voice-current appears, it has a certain meaning which I will now explain. A voice-current in this connection or as meant herein by me is a current circulating through the line, receivers, and secondaries of the inductoria and produced or generatcd by the agency of the human voice. It is of an undulatory character. As is well understood, the undulations of such currents, if graphically reproduced,resemble graphicallyreproduced sound-waves. In the working of this system the line when in full operation carries a plurality of voice-currents difiering in certain respects from each other, and whenever in the specification and claims the term ability to select voice-currents occurs I mean that the apparatus is capable of selecting one out of the said plurality of currents and causing the same to operatively adect the receiving instrument, rendering all the other currents of the said plurality of currents ineffective in this particular instance.

Wherever the term adjustment of the instruments in pairs occurs it means that like conditions or adjustments as to the ability to select voice-currents are brought about in two instruments simultaneously.

The instruments of my system have a pl urality of possible speaking conditions, under each of which speech can be transmitted. The speaking conditions I number 1 2 3, (to. Now, supposing all the instruments are at rest, I send a signal to any one of the distant stations with the effect that the station called and my own are brought into condition 1, and this condition is now inaccessible to all other stations so long as I remain in communication with the station which I have called. If now a second pair of stations enter into conversation, they preempt to second speaking condition, and this is likewise made inaccessible to all the other pairs while communication lasts between this second pair. The third pair of instruments switched onto the line now takes up the third speaking condition, and so on until the limit of the system is reached. In other words, the speaking conditions 1 2 3, &c., are taken up by the pairs of instruments in the order in which said pairs are switched onto the line. If any speaking condition becomes idle by reason of a pair of intercommunicating instruments being placed out of use, all instruments working under a speaking condition of a higher number than the one becoming idle will switch to the speaking condition having the next lower number; but the instruments working under a speaking condition of a lower number than that becoming idle will not be changed in any way.

The meaning of the term speaking conditions as employed by me herein I will now explain. Each instrument is capable of assuming any one of a plurality of predetermined adjustments, each adjustment having the effect of producing certain changes in the electrical connections of the instruments, and the different conditionsof the instruments resulting from these predetermined adjustments are what I refer to by the term speaking conditions.

The sending and receiving instruments at the stations,which are respectively adjustable as to their ability to send and select voicecurrents, include a plurality of adjustable elements. In the present instance these elements consist of the adjustable condenser, the adjustable inductorium, and the adjustable receiver. It will be understood, however, that where I employ the term instruments herein I do not wish to limit myself to this combination of elements, but said term is intended to include any elementor combination thereof which will send or select voicecurrents.

I claim as my invention- 1. A system of multiplex transmission of speech over a single line comprising instruments at the different stations adjustable as to their ability to send and select voice-currents, controlling means at the different stations for effecting the adjustment of the instruments in pairs and selecting means for actuating said controlling means.

2. A system of multiplex transmission of speech over a single line comprising instruments at the different stations adjustable as to their ability to send and select voice-currents, means for effecting the adjustment of the instruments in pairs and automaticallyoperated controlling devices for said means, substantially as described.

3. A system of multiplex transmission of speech over a single line comprising instruments at the different stations adjustable as to their ability to send and select voice-currents, controlling means for effecting the adjustment of the instruments in pairs, signaling and selecting means for actuating said controlling means. l

4. A system of multiplex transmission of speech comprising instruments adjustable as to their ability to send and select voice-cur rents, signaling and selecting apparatus, controlling means at the stations adapted to adj ust the instruments,said controlling means comprising means controlled by the receivers and means controlled by the signaling and selecting apparatus, said controlling means being rendered efiective in adjusting the in struments when the receivers are taken down, substantially as described. 3

5. A system of multiplex transmission of speech comprising instruments adjustable as to their ability to send and select voice-01m rents, signaling and sympathizing apparatus, controlling means at the stations adapted to adjust the instru ments and comprising means controlled by the receivers and means controlled by the signaling and sympathizing apparatus, said controlling means being rendered effective in making the adjustments in the instruments when the receivers are taken down, substantially as described.

6. A system of multiplex transmission of speech, comprising instruments adjustable as to their ability to send and select voice-currents, controlling means at the different stations for adjusting the instruments and signaling and sympathizing apparatus for setting the said controlling means substantially as described.

7. In combination in a system of multiplex transmission of speech, the receivers, condensers and inductoria in the stations, said receivers and inductoria being adjustable as to their windings and the condensers being adjustableas to their capacity, switches for changing the electrical connections of the parts and signaling and sympathizing apparatus for controlling the switches, substantially as described.

8. In combination in a system of multiplex transmission of speech, receivers adjustable as to their windings, inductoria adjustable as to their windings, condensers adjustable as to their capacity, electrical connections between the receivers, indnctoria and condensers and means for effecting the adjustment of the said parts simultaneously; transmitters and a line conductor, substantially as described.

9. In combination in a system of multiplex transmission of speech, receivers adjustable as to their windings, inductoria adjustable as to their windings, transmitters, electrical connections and switches for adjusting the wind ing of the receivers and the inductoria simultaneously, substantially as described.

10. A system of multiplex telephony comprising sending and receiving instruments adj ustable as to their ability tosend and select voice-currents, a conductor and means controlled by the manipulations necessary to establish communication, said means effecting like adjustments in the intercommunicating instruments and unlike adjustments between said instruments and all others in the system, substantially as described.

11. A system of multiplex telephony comprising sending and receiving instruments adjustable as to their ability to send and select voice-currents, a single line between all of said instruments, means for effecting like adjustments in the intercommunicating instruments and unlike adjustments between said instruments and all others in the system, and signaling and selecting apparatus controlling said means, substantially as described.

12. A system of multiplex telephony comprising sending and receiving instruments in the stations adjustable as to their ability to send and select voice-currents, a single line connecting them, controlling means for effecting like adjustments in the intercommunicating instruments and unlike adjustments between said instruments and others in the system, signaling apparatus for setting said means, the said controlling means being rendered effective by the manipulation of the receiver, substantially as described.

13. A system of multiplex telephony comprising sending and receiving instruments in the stations adjustable as to their ability to send and select voice-currents, a single line connecting them, controlling means for-effectinglike adjustments in the intercommunicating instruments and signaling, selecting and sympathizing apparatus with electrical connections for controlling said means whereby intercommunicating stations have like adjustments existing therein while unlike adj ustments exist between said stations and all others, substantially as described.

14. A system of multiplex telephony com prising sending and receiving instruments at the various stations adjustable as to their ability to send and select voice-currents, a single line, means whereby like adjustments are effected in intercommunicating instruments and means whereby adjustments are effected in all the idle stations step by step as the pairs of instruments in the system are successively brought into use, substantially as described.

15. Asystem of multiplex telephony comprising sending and receiving instruments adjustable as to their ability to send and select voice-currents, at the various stations, a single line, means whereby like adjustments are eifected in intercommunicating instruments and whereby adjustments are effected in all the idle stations step by step as the pairs of instruments in the system are successively brought into use, said adjustments being rendered effective in changing the selective nature of each new pair of instruments as they are brought into use by taking down the receivers of said instruments, substantially as described.

16. A system of multiplex telephony comprising sending and receiving instruments at the various stations adjustable in pairs as to their ability to send and select voice-currents, a single line, means in each station whereby both instruments of each pair of intercommunicating stations are given like adjustments in establishing communication to sympathize with one another and are both adjusted out of sympathy with the other instruments and means controlled at the calling station for operating the sympathizing means.

17. A system of multiplex telephony comprising a plurality of receivers adjustable as to their resistance, means controlled by the operator for changing the said resistance in pairs of instruments, suitable transmitters and a line conductor, substantially as described.

18. A system of multiplex telephony com-- prising receivers adjustable as to their resistance and means controlled by the operators for changing the said resistancein pairs of instruments step by step as the pairs of instruments are brought into use in succession, substantially as described.

19. A multiplex system of telephony comprising sending and receiving instruments adjustable as to their ability to send and select voice-currents, means for effecting adjustments in the instruments step by step as the pairs of instruments are brought into use successively, and means whereby the system is restored to normal position step by step as the pairs of instruments are successively placed out of use, substantially as described.

20. A system of multiplex telephonycomprising instruments adjustable as to their ability to send and select voice-currents in the stations, controlling means for adjusting the instruments, signaling apparatus, means in the calling and called stations for preventing system for adjusting the controlling devices when said signalis sent, substantially as de-.

scribed.

22. A system of multiplex telephony comprising instruments in the stations adjust-I able as to their ability to send and select voicecurrents, means for adjusting the instruments as to their ability to select voicecurrents, means operating step by step for restoring the instruments to normal condition and for maintaining the relative diit'erence in adjustment between the pairs of in struments while said instruments are being restored step by step to normal condition, substantially as described.

23. In combination, in a telephone system, instruments in the stations adjustable as to their ability to send and select voice-currents, controlling means for adjusting the instruments, settingmechanism for said controlling means and obstructing means to prevent said setting means from operating, said obstructing means including a manually-operated de vice acting upon the controlling means and an electrically-operated device also acting upon the controlling means, substantially as described.

24. In combination in a telephone system, instruments in the stations adjustable as to their ability to send and select voice-currents, controlling means for adjusting the instruments, a signaling-circuit and a Morse key controlling said circuit, said Morse key acting also as a mechanical obstructor at the calling station, for the said controlling means and an electrically-operated obstructor at the called station for the controlling means at that station, said electrical obstructor being controlled through the signal-circuit substantially as described.

25. In combination in a telephone instruments in the stations adjustable as to their ability to send and select voice-currents, controlling means for adjusting the instruments as to their ability to select voice-currents, a signaling-circuit, each station having a Morse key, a setting device and an electrically-operated obstructing device said obstructin g device serving to prevent the operation of the setting device at the called station, a mechanical obstructor at the calling station to prevent the operation of the controlling means at the calling station andselecting system,

means whereby the electrical obstructing device at the called station only is rendered active, substantially as described.

26. In combination in a telephone system instruments in the stations adjustable as to their ability to send and select voice-currents, controlling means for effecting the adjustment of the instruments, setting means for the said controlling means, electrically-operated obstructing means and manually-operated obstructing means for the setting means and resetting means to restore the instruments to normal position, substantially as described.

27. In combination in a telephone system, instruments in the stations adjustable as to their ability to send and select voice-currents, means for effecting the adjustments in the instruments, including resetting means, a resetting-circuit, circuit-closers, gravity-hooks for operating the same and a circuit-breaker whereby only one of said circuit-closers is rendered effective in establishing the resetting-circuit so that only one resetting impulse will result from each use of a pair of instruments, substantially as described.

28. In combination in a telephone system, instruments in the stations adjustable as to their ability to send and select voice-currents, means for effecting the adjustments in the instruments, including resetting means, a resetting-circuit, circuit-closers operated at the called and calling stations by hanging up the receivers, and means whereby only one of said circuit-closers is rendered effective in establishing the resetting-circuit so that only one resetting impulse will result from each use of a pair of instruments, said means comprising a circuit breaker operated by the Morse keyat the calling station, substantially as described.

29. In combination, in a multiplextelephone system, instruments in the stations adjustable as to their ability to send and select voice-currents, means for effecting the adj ustments in the instruments, comprising a. switch and a selecting or stop lever, a setting means comprising an armature and magnet to operate the lever, an electrically-controlled obstructing device for the setting means, a sig naling-circuit, a Morse key arranged to obstruct orlock the lever and resetting means to operate the lever, substantially as described.

30. In combination, in a multiplex telephone system, adjustable condensers, adjustable inductoria and adjustable receivers in the stations, means for changing the connections between said parts comprising a switch having a plurality of series of contacts to coin nect certain sections of the said parts in each station in series or in parallel, and means for controlling the position of said switch, substantially as described 31. In combination in a multiplex tele phone system, the adjustable condensers, adj ustable inductoria and adjustable receivers, a switch D having a plurality of series of con tacts adapted to connect certain sections of the said parts in series or in parallel, a gravityhook for returning and holding the switch in its inactive position, a stop-lever for holding the switch in either of its operating positions, and means con trolling the position of the said lever, substantially as described.

32. In combination in a multiplex telephone system, an adjustable condenser, an adjustable inductorium and an adjustable receiver in each station, a switch having aplurality of contacts, the parts of the instruments being adapted to be connected up in series or in parallel by the said switch, a stop-lever to control the switch, a setting-magnet with its armature acting upon the stop-lever and a resetting-magnet having its armature arranged to control the resetting action of the stop-lever, substantially as described.

33. In combination in a multiplex telephone system, the instruments adjustable as to their ability to send and select voice-currents, controlling means for adjusting the instruments comprising switches D having a plurality of series of contacts, stop-levers I for engaging said switches, said levers having toothed portions, the setting and resetting magnets with their armatures acting upon the said toothed portions, the resetting-circuit, a local circuit-breaker U for said circuit and a signaling device adapted to operate the circuit-breaker at the calling station.

34:. In combination, in a multiplextelephone system, instruments adjustable as to their ability to send and select voice-currents, means foradjustingtheinstruments at the several stations including setting and resetting devices, a resetting-circuit,resetting-switches and receiver-hooks to which the resettingswitches are connected, said switches comprising a series of contacts, means for holding the contacts out of engagement as the switches move one way and for allowing the said contacts to engage as the switches move the other Way, substantially as described.

35. In combination, in a multiplex-telephone system, instruments adjustable as to their ability to send and select voice-currents, controlling means for adjusting the instruments, setting devices for said means, a resetting device, a resetting-circuit, a circuitbreaker U at the calling station, the receiverhook and resetting-switch connected therewith, said switch being arranged to mechanically close the circuit-breaker U, substan tially as described.

36. In combination in a multiplex telephone system, instruments adjustable as to their ability to send and select voice-currents, controlling ineans for adjusting the instruments, resetting means for the controlling means and resetting-switches, each of said switches comprising a movable switch-arm, a fulcru med lever, the said moyable switch-arm carrying a plurality of contacts, and carrying also a movable part and the said fulcrumed lever having also a plurality of contacts and cam-surfaces adapted to engage said movable part whereby on one strokeof the switch the contacts will engage while on the other stroke they will be held out of engagement, substantially as described.

37. A system of multiplex transmissions of speech over a single line comprising instruments at the different stations, each of which is capable of assuming any one of a plurality of speaking conditions and means for causing the instruments to select the speaking conditions in a predetermined order as the pairs of instruments are successively placed into use, substantially as described.

38. A system of multiplex transmissions of speech over a single line, comprising instruments at the different stations each of which is capable of assuming any one of a plurality of speaking conditions and means for causing the instruments to select and release the speaking conditions in a predetermined order as the pairs of instruments are successively placed into and out of use, substantially as described.

39. In combination in asystem of multiplex transmission of speech, receivers adjustable as to their windings, inductoria each having asecondary subdivided into sections, a transmitter and battery connected with the primary of each inductorium, electrical connections and means for adjusting the windings of the receivers and of the secondary of the inductoria, substantially as described.-

In testimony whereof I affix my signature in presence of two witnesses.

ERNEST A. FALLER.

Witnesses:

JNo. OHOGAN, UPTON H. RIDENOUR, Jr. 

